代碼分析資料蒐集數據分析與處理之二（Leveldb 實現原理） LevelDB Cache實現機制分析學習筆記：The Log（我所讀過的最好的一篇分佈式技術文章）

 1 //
 2 // Created by penglei on 18-9-29.
 3 //
 4 
 5 #ifndef TOOLS_MEASUREALGOTIME_HPP
 6 #define TOOLS_MEASUREALGOTIME_HPP
 7 
 8 #include <chrono>
 9 #include <type_traits>
10 #include <iostream>
11 
12 namespace Tools {
13 
14     namespace Time {
15 
16         using ns = std::chrono::nanoseconds;
17         using us = std::chrono::microseconds;
18         using ms = std::chrono::milliseconds;
19         using s = std::chrono::seconds;
20         using m = std::chrono::minutes;
21         using h = std::chrono::hours;
22 
23         template <typename DurationType> class AlgoTime;
24         using AlgoTimeNs = AlgoTime<ns>;
25         using AlgoTimeUs = AlgoTime<us>;
26         using AlgoTimeMs = AlgoTime<ms>;
27         using AlgoTimeS = AlgoTime<s>;
28         using AlgoTimeM = AlgoTime<m>;
29         using AlgoTimeH = AlgoTime<h>;
30 
31         /**
32          * 用於計算代碼運行的時間
33          * @tparam DurationType 相似於時間單位，默認以「毫秒」爲單位
34          */
35         template <typename DurationType = ms>
36         class AlgoTime {
37         public:
38             void start() {
39                 start_  = std::chrono::steady_clock::now();
40             }
41 
42             typename DurationType::rep elapsed() const {
43                 auto elapsed = std::chrono::duration_cast<DurationType>(
44                         std::chrono::steady_clock::now() - start_);
45                 return elapsed.count();
46             }
47 
48             void printElapsed() {
49                 auto time = elapsed();
50 
51                 if (std::is_same<DurationType, ns>::value) {
52                     std::cout << std::endl << "[AlgoTime: " << time << " ns]" << std::endl;
53                 } else if (std::is_same<DurationType, us>::value) {
54                     std::cout << std::endl << "[AlgoTime: " << time << " us]" << std::endl;
55                 } else if (std::is_same<DurationType, ms>::value) {
56                     std::cout << std::endl << "[AlgoTime: " << time << " ms]" << std::endl;
57                 } else if (std::is_same<DurationType, s>::value) {
58                     std::cout << std::endl << "[AlgoTime: " << time << " s]" << std::endl;
59                 } else if (std::is_same<DurationType, m>::value) {
60                     std::cout << std::endl << "[AlgoTime: " << time << " m]" << std::endl;
61                 } else if (std::is_same<DurationType, h>::value) {
62                     std::cout << std::endl << "[AlgoTime: " << time << " h]" << std::endl;
63                 }
64             }
65 
66         private:
67             std::chrono::steady_clock::time_point start_;
68         };
69 
70     } // namespace Time
71 
72 } // namespace Tools
73 
74 #endif //TOOLS_MEASUREALGOTIME_HPP

View Code

 1 #include "MeasureAlgoTime.hpp"
 2 
 3 int main() {
 4 
 5     // 建立一個以「微秒」爲單位的算法時間對象
 6     // 固然也能夠使用其它時間單位的時間對象，如毫秒、秒等
 7     Tools::Time::AlgoTimeUs time;
 8     
 9     // 啓動計時
10     time.start();
11     for (int i = 0; i < 1024; ++i) {
12         std::cout << "hello C++11 !" << std::endl;
13     }
14 
15     // 直接在標準輸出設備中輸出程序的運行時間
16     time.printElapsed();
17     
18     // 或者使用如下方式進行運行時間的輸出
19     auto elapsed = time.elapsed();
20     std::cout << elapsed << "us" << std::endl;
21     
22     return 0;
23 }